Multivariate management of entrained air and rheology in cementitious mixes

ABSTRACT

The invention relates to a method and system for monitoring and adjusting both air content and rheology (e.g., slump, slump flow) properties of a hydratable concrete mix contained within a concrete mixer. The system simultaneously tracks dosage of both rheology-modifying admixture (e.g., polycarboxylate polymer cement dispersant) and air control agent or “ACA” (e.g., air entraining agent) by reference to at least four nominal dose response (“NDR”) curves or profiles, which at least four NDR profiles are based on the respective behaviors of each of the ACA and rheology-modifying agent on air content and rheology.

FIELD OF THE INVENTION

The present invention relates to the manufacture of concrete, and moreparticularly to a method for monitoring and adjusting entrained air andrheology (e.g., slump, slump flow) properties in a fresh concretecontained in a concrete mixing drum using a process control system.

BACKGROUND OF THE INVENTION

In U.S. application Ser. No. 11/834,002, Sostaric et al. disclosed thatplasticizers and air entraining agents can be dosed into the concretecontained in the mixing drum of a delivery truck using a process controlsystem. However, it was not explained how rheological properties, on theone hand, and, air properties, on the other hand, could besimultaneously controlled.

It has been known, however, that “slump” or fluidity can be individuallymonitored and adjusted using a process control system. This is done bymeasuring the energy required for rotating concrete in a mixing drumusing various sensors; correlating energy values with slump values(using a standard slump cone test); and storing this information inmemory so that a computer processing unit (“CPU”) can correlate theenergy and slump values. See e.g., U.S. Pat. Nos. 4,008,093, and5,713,663. As concrete stiffens over time, due to hydration,evaporation, and/or other factors, greater energy is required to rotatethe drum, and the CPU can be programmed for activation of devices toinject water or chemical dispersant into the concrete mix.

Numerous patents have declared that various properties of concrete mixescan be monitored and adjusted through the use of sensor devices that areconnected to a CPU. For example, in U.S. Pat. No. 5,713,663, Zandberg etal. deployed sensors for measuring amounts of batch water andparticulate ingredients, sand moisture content, time, and other factors(See e.g., col. 8, lines 3-14). In US Patent Publication No.2009/0037026, Sostaric et al. referred to sensors for detecting mixingdrum temperature, rotational speed, “acceleration/deceleration/tilt,”vibration, and other properties. These and other prior art publicationscontain the common suggestion that data gathered by the sensors can belisted in “look up” charts.

However, for all of these prescriptions concerning the usefulness ofsensor-derived data, the monitoring and controlling of rheology (e.g.,slump) and entrained air content have not been accurately or reliabilityachieved or integrated in practice. Although it is generally known thatchanging the air content affects slump and vice versa, the concreteindustry has not able to predict what the slump of a concrete mix mightbe, for example, by doubling or multiplying entrained air levels. Inother words, while slump might be increased as a general proposition byincreasing air content, the precise extent to which slump is increasedhas not been reliably predicted based on how much air entrainingadmixture (“AEA”) is introduced into the concrete mix. As a result,prior art devices have focused only on adjusting slump or otherrheological property in the truck.

For concrete without AEA, adding cement dispersant typically hasnegligible effect on air content and prior art devices were designedonly for adjusting slump. However, in air entrained concrete, thepresent inventors realize that changing rheology by adding cementdispersants substantially affects air content. They believe that anintegrated approach to controlling both rheology and air content isneeded for such cases.

The problem is that there is no consistent or linear correlation betweenrheological properties such as slump and the use of AEAs in concretemixes. This is due largely to the nature of concrete, which isinconsistent from batch to batch, and even from day to day. Many factorslead to this inconsistency: including variability in batch mix design,ingredient quality and source, processing conditions (e.g., temperature,humidity, revolutions needed for particular mixing drum), and nature ofdispersant and AEA employed. As further explained hereinafter, chemicaldispersants and AEAs may have adverse and unpredictable effects on theperformance of the other.

The prior art is devoid of precise teachings about how to administerAEAs and dispersants using an integrated approach in a concrete mixer.The present inventors believe that the number of problems created byAEAs for ready-mix producers, contractors, and owners far exceed thosecreated by all other admixtures. Almost everything influences theperformance of AEAs: e.g., ambient and concrete temperatures, traveltime from plant to site, mixing time, cement type, and the nature andvariability of cement dispersants (particularly polycarboxylatesuperplasticizers).

There are different types of air in concrete: entrapped air andentrained air. “Entrapped air” results from the mixing process, wherebyair is mechanically enfolded (usually 1.5% by concrete volume) bychurning aggregates or moving paddles within the mixing drum. Suchentrapped air is visible to the eye as irregularly shaped voids whenviewed, for example, in a sawn cross-section of hardened concrete. Onthe other hand, “entrained air” has the form of microscopic, sphericallyshaped voids; it thus becomes more easily distributed throughout themix. The sizing and spacing of entrained air bubbles is important forenhancing durability of concrete subjected to freeze/thaw conditions.Air entraining admixtures are used to form and to stabilize thesemicroscopic voids in the concrete.

What complicates matters is that typical measurement of entrained air inconcrete involves a percentage reading of the total amount of air, whichis to say both “entrapped” and “entrained” air. Where the percentagereading is 6% air, for example, this means approximately 1.5% of thetotal air is entrapped, while 4.5% is entrained air.

Further complicating matters is the fact that the concrete mixing drumand the motion of the delivery truck, which is jostled by travel overirregular roadways and surfaces, can increase the relative amount of“entrapped” air. On the other hand, the longer the time that theconcrete is being transported in the truck, the more the free watercontent in the concrete decreases due to evaporation and hydration. Aswater is necessary for air bubble formation, the percentage of totalair, including entrained air, can decrease.

A still further complicating factor is that different kinds of AEAs havedifferent effects on bubble formation in the concrete mix and can beinfluenced differently depending on the type of dispersant used.

A wood-derived salt type AEA, such as Vinsol resin, is often used in lowwater concrete mixes to obtain a good bubble structure. When asuperplasticizer is added, such as to obtain a higher slump at pour,entrained air levels tend to decrease. This continues the longer theconcrete is mixed in the truck. Addition of air entraining admixture isthus required for this situation.

On the other hand, a synthetic resin type AEA (e.g., fatty acid salts ortall oil) works differently in that it tends to entrain more smallbubbles as slump increases. Thus, if water is added to the concrete mixat pour, the amount of entrained air can increase potentially toexcessive levels in certain situations.

In view of the foregoing, the present inventors believe that a novelmethod and automated process control system is needed for integratingand simultaneously monitoring and adjusting both air and rheologyproperties, using separate component additions of an air controladmixture component and a rheology control admixture component, whichhitherto have had unpredictable and adverse effects upon each other andupon the resultant concrete mix.

SUMMARY OF THE INVENTION

In surmounting the disadvantages of prior art, the present inventionprovides a method and process control management system for monitoringand adjusting air and rheology (e.g., slump, slump flow, yield stress)in hydratable cementitious mixes such as concrete in a mixing drum.

The system and methods of the invention are suitable for adjustingproperties of concrete in a mixing drum through automated monitoring andcontrolled addition of additives, including at least one cementdispersant comprising water, polymer dispersant, or mixture thereof; andincluding at least one air controlling admixture (ACA) such as an airentraining admixture (AEA), an air detraining admixture (ADA), or amixture thereof (AEA/ADA).

An exemplary system and method of the invention for monitoring andadjusting entrained air level and rheology in a hydratable cementitiousmix, comprises:

(a) providing a concrete mix in a concrete mixer, said concrete mixcomprising hydratable cement, aggregates, and water for hydrating saidcement, and said concrete mix having a total volume when mixed uniformlyof 1.0 to 15.0 cubic yards;

(b) inputting into a computer processing unit (CPU) and storing intocomputer accessible memory desired concrete performance ranges relativeto:

-   -   a rheology target or target range (hereinafter “R_(T)”) wherein        a desired concrete slump or slump range is specified within a        range of 0-11 inches (e.g., slump as determined based on        standard slump cone test in accordance with ASTM C143-05 or        other standard test); and    -   an air content target or target range “A_(T)” wherein a desired        concrete air content or air content range is within a range of        1% to 10% (which may be determined in accordance with standard        tests set forth in ASTM C138-10, C173-10, and/or C231-10 or        other standard test);

(c) operating said concrete mix in said rotatable concrete mixer andobtaining at least one rheology value in current time (hereinafter“R_(CT)”) and at least one air content value in current time(hereinafter “A_(CT)”);

(d) comparing using CPU said R_(CT) against said R_(T) and said A_(CT)against said A_(T) until detection by CPU of a non-conformance eventwherein said R_(CT) does not conform with said R_(T) and/or said A_(CT)does not conform with said A_(T); and

(e) introducing into the concrete mix contained in said concrete mixer,one of at least two different types of additives comprising:

-   -   at least one admixture for modifying entrained air level in the        concrete mix (hereinafter “ACA”) wherein said at least one ACA        comprises Air Entraining Admixture (hereinafter “AEA”), Air        Detraining Admixture (“ADA”), or mixture thereof; and    -   at least one cement dispersant for modifying rheology of the        concrete mix, said at least one cement dispersant comprising a        polymeric cement dispersant, water, or mixture thereof;        said introducing of said at least one ACA and cement dispersant        being achieved by CPU-controlled valve system in accordance with        CPU-accessed memory device having at least four sets of data        correlations: namely, (i) effect of said cement dispersant on        rheology (e.g., slump); (ii) effect of said ACA on air        content; (iii) effect of said ACA on rheology (e.g., slump);        and (iv) effect of said cement dispersant on air content. The        present invention can be employed for monitoring and controlling        rheology properties such as slump, slump flow, and yield stress        of the fresh hydratable cementitious composition.

Thus, systems and methods of the invention involve introduction of AEAs(air entraining admixtures), ADAs (air detraining admixtures, or“defoamers), or combinations of AEAs and ADAs. Preferred embodimentsinvolve introducing AEA and polycarboxylate polymer cement dispersantinto a concrete mix. These are among the most problematic of chemicaladmixtures combinations to administer.

In preferred systems and processes of the invention, each of saidcorrelations above-described in Paragraph (e)(i) through (e)(iv) isbased on a set of data wherein respective amounts of the at least oneACA (as mentioned in steps “(e)(ii)” and “(e)(iii)”) and at least onecement dispersant (as mentioned in steps “(e)(i)” and “(e)(iv)”) aredetermined using nominal dosage response (“NDR”) profiles. The NDRprofiles are based on an average of at least two, and more preferably ofa plurality (more than three) of, dosage/effect curves, as will beexplained in further detail hereinafter. These NDR profiles do notrequire time-consuming compilations to be placed into “lookup tables” ofparameters by the operator. These NDR profiles minimize the task ofinputting numerous parameters at the outset of each batch preparation ordelivery. A dose response curve represents a correlation between thedose amount of water and/or chemical admixture or admixtures to aproperty of the concrete that is modified by the effect of the waterand/or chemical admixtures. The dose response curve may be representedin one of a number of forms, for clarity and convenience, and for easeof CPU programming. For instance, a dose response curve for a chemicaladmixture that modifies slump can be represented as the administereddose to the slump of the concrete. Alternatively, the dose responsecurve can be represented as the change in chemical admixture dose (orwater) needed to change the slump by one incremental unit, for example,the dose needed to change slump by one inch (e.g., to change slump from2 inches to 3 inches).

For purposes of the present application, a dose response curve for agiven set of materials under a certain set of conditions which can belater used to select the proper dose during concrete production isreferred to herein as the nominal dose response (“NDR”) curve. Becausethe dose response curve is a function of a large number of variables(material properties, temperature, etc.), it is impractical to developdose response curves that specifically involve consideration of allrelevant variables, to program a CPU with look-up tables or the likewhich lists these specific variables, to measure all of these variables,and then to select the correct dose of the rheology-modifying agent(e.g., chemical admixture) to achieve a desired response. Thus,preferred methods and systems of the invention will employ the use ofNDR profiles or curves based on data correlations.

It is a further objective of this invention to provide a means forefficiently and accurately updating nominal dose response (“NDR”) curveinformation of both entrained air level data and rheology (e.g., slump)data. This will address the problems of specific external variableswhile avoiding having to take these variables into account explicitly.The present inventors surprisingly realized that when NDR curves aregenerated for both entrained air level and rheology level for eachadditive to be incorporated into concrete, then both air and rheologyproperties can be simultaneously, adaptively controlled through a novel,highly inventive yet elegant control methodology which is the subjectmatter of the present invention.

The present invention arises from two surprising discoveries: first,that concrete mixes have different parameters (e.g., temperature, mixdesign, water levels, hydration levels, humidity, different trucks) anddisplay “dose response” profiles that vary in amplitude but otherwisehave similar behavior in that their dosage response curves do notintersect; and, second, that the “dose response” profiles of theafore-mentioned four correlations of Paragraph (e)(i) through (e)(iv)can be monitored and adjusted, such that entrained air and rheologytargets can be attained in integrated fashion. For example, if anarchitect or job supervisor requests delivery of a fresh concrete mixhaving a slump (rheology) target of, for example, “4 to 6 inches” (inreference to standard vertical slump cone test) and an entrained aircontent target of, for example, “4 to 6 percent,” the systems andmethods of the present invention can be deployed to achieve theseperformance targets based on known slump and air content monitoringequipment and known chemical admixtures. Such capability has notpreviously been attained or suggested in the concrete industry.

Further advantages and specific feature details of the invention aredescribed hereinafter.

BRIEF DESCRIPTION OF DRAWINGS

Further advantages and features of the present invention may be morereadily comprehended when the following detailed description ofpreferred embodiments is taken in conjunction with the appended drawingswherein

FIG. 1 is a graphic illustration of the exemplary method of the presentinvention in which, for a given concrete mix, the current air contentand slump (rheology) designated at “1” are determined and compared withair content (range) target (“A_(T)”) and slump target (“S_(T)”),together represented by the rectangle designated at “2”; and, wherenon-conformance is determined, the air and slump are adjusted by addingair entraining agent and/or cement dispersant based on at least foursets of data correlations: wherein the respective effects on both aircontent and slump are correlated with each of air entraining agentdosage increases (as illustrated by arrow designated at “3”) and ofcement dispersant dosage increases (as illustrated by arrow designatedat “4”), the cumulative effects of which are illustrated by the arrowdesignated at “5” (indicating that entrained air and slump of theconcrete mix have been brought within target ranges for A_(T) andS_(T));

FIG. 2 is a graphic illustration of current slump (inches) of concreteplotted as a function of the amount of rheology modifying agent (e.g., acement dispersant referred to as a High Range Water Reducer or “HRWR”)required to change slump by one inch;

FIG. 3 is a graphic illustration of entrained air content (%) ofconcrete as a function of the amount of Air Controlling Admixture (e.g.,an Air Entraining Agent or “AEA”) required to change air content by onepercent;

FIG. 4 is a graphic illustration of current slump (inches) of concreteplotted as a function of the amount of AEA required to change slump byone inch;

FIG. 5 is a graphic illustration of entrained air content (%) ofconcrete plotted as a function of the amount of HRWR required to changeair content by one percent;

FIG. 6 is a graphic illustration of alternative method of the presentinvention whereby current slump (inches) of concrete is measured as afunction of the ratio of amount of the amount of change in entrained aircontent (%) divided by the amount of change in slump (inches) for agiven dosage of a chemical admixture;

FIGS. 7 and 8 are graphic illustrations of other dose response curvesfor concrete mixes whereby the initial slump (horizontal axis) isexpressed against the dose required to increase slump by one unit(vertical axis); and

FIG. 9 is a graphic illustration wherein actual measured slump changevalues (shown by the dots) are seen to closely match theoretical slumpchange values in accordance with nominal dosage response curves orprofile, based on testing of cement dispersant on slump of concrete mix.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The term “cementitious” refers to Portland Cement and/or cementsubstitutes (fly ash, blast furnace slag, limestone, pozzolan, etc.)which, when mixed with water, bind together fine aggregates such as sandinto mortar, and, additionally, coarse aggregates such as crushed stoneor gravel into concrete. These materials are “hydratable” in that theyharden when mixed with water to form building materials and engineeringstructures.

It is contemplated that conventional cement dispersants and aircontrolling admixtures (“ACA”) may be employed in the present invention,as well as other optional admixtures for modifying the rheology andentrained air of cementitious compositions such as mortars andconcretes. In addition, any admixture that results in a change inrheology or air content, whether as the main effect or non-main (e.g.secondary) effect, can be managed using the methodology describedherein.

For purposes of illustration, the rheology property known as “slump”will be discussed and illustrated herein. However, it is understood thatthe rheological properties known as “slump flow” and “yield stress” arerelated properties of fresh cementitious materials (e.g., concrete) thatcan also be monitored and controlled using the teachings of the presentinvention.

Known cement dispersants which can be used in the present inventioninclude conventional plasticizers (including superplasticizers). Theseinclude lignosulfonates, naphthalene sulfonates, melamine sulfonates,hydroxycarboxylic acids, oligosaccharides, and mixtures thereof. Otherknown cement dispersants include plasticizers having oxyalkylene groups(e.g., ethylene oxide, propylene oxide, or mixtures thereof),polycarboxylic acid groups (or their salts or esters); or mixturesthereof. Many of these types of cement dispersants, some of whichcontain thickeners and other viscosity modifying agents for improvedstability or other attributes, are available from Grace ConstructionProducts (Cambridge, Mass.) under various trade names, such as DARACEM®,WRDA®, ADVA®, and MIRA®, and these are all deemed suitable cementdispersants which can be used in the present invention.

The term “cement dispersant” and “dispersant” as used herein shall meanand refer to water and to plasticizers which facilitate dispersion ofhydratable cement particles within an aqueous suspension. In suchcontext, it is understood that the term “plasticizer” refers to “waterreducing” agents that allow hydratable mortars or concretes to be madeusing less water. “Superplasticizers” are thus termed because theypermit 12% or more of water to be replaced in the cement paste portion.Such plasticizing agents are conventionally known.

Moreover, for purposes of the present invention, conventional cementdispersants may be employed containing one or more air controllingadmixtures (“ACA”) pre-mixed into the product formulation. It iscontemplated that methods and systems of the invention includecommercially available cement dispersant formulations to be used as the“cement dispersant” component, in combination with dosing of anadditional, separate ACA component. For example, U.S. Pat. No.7,792,436, owned by W. R. Grace & Co.-Conn., disclosed polycarboxylatecement dispersant formulated with air controlling admixtures, and thiscould be administered into the concrete mix as the “cement dispersant”component, and the same or different air controlling admixtures(entrainers and/or detrainers) can be separately dosed as the ACAcomponent.

In other exemplary methods and systems of the present invention, it canbe advantageous to use cement dispersants having comparatively quickmix-in dispersibility to expedite monitoring and adjustment of theconcrete mix properties. In U.S. Pat. No. 8,085,37781, for example,Goc-Maciejewska et al. taught phosphate-containing polycarboxylatedispersants having oxyalkylene groups, acrylic acid groups, and estergroups for achieving quick mix-in dispersibility when using concrete mixequipment.

Known air controlling admixtures (“ACAs”) suitable for use in thepresent invention include conventional Air Entraining Agents (“AEAs”) aswell as conventional Air Detraining Agents (“ADAs”) (sometimes referredto as defoamers). Conventional AEAs include water soluble salts (usuallysodium) of wood resin, wood rosin, or gum rosin; non-ionic surfactants(e.g., such as those commercially available from BASF under the tradename TRITON X-100); sulfonated hydrocarbons; proteinaceous materials; orfatty acids (e.g., tall oil fatty acid) and their esters.

AEAs believed suitable for purposes of the present invention areavailable from Grace Construction Products under the trade names DAREX®,DARAVAIR®, and AIRALON®.

Known air detraining admixtures (“ADAs”) believed to be useful in theinvention include tributyl phosphate, propoxylated amines, silicone, andmixtures thereof.

The term air controlling admixtures “ACAs” as used herein encompassessurface active agents and combinations thereof, and may involve bothentraining and detraining properties, or otherwise have componentshaving different effects on the air properties. For example, U.S. Pat.No. 7,792,436, as previously referenced above, discloses a combinationinvolving (a) a first surface active agent comprising betaine, an alkylor aryl or alkylaryl sulfonate, or mixture thereof, for the purpose ofincreasing air content in the concrete; and (b) a second surface activeagent comprising a nonionic oxyalkylene-containing polymer surfactantfor providing a fine and uniform air void distribution (with somedetraining properties) within a suitable 3-20 percent range based onconcrete volume. Thus, the present inventors contemplate that exemplaryACAs may be used having both entraining and detraining properties, suchas for controlling both the quantity and quality of entrained air (e.g.,size and spacing) with the (eventually hardened) concrete matrix.

The “ACA” component, similar to the cement dispersant component, maycomprise a portion of one or more cement dispersants in addition to AEAand/or ADA. Indeed, additional conventional concrete admixtures may beincorporated into either or both of the “ACA” and “cement dispersant”components for added performance values, and these include setaccelerators, set retarders, and the like.

Concrete delivery mixing trucks having slump control monitoring andcontrol equipment, such as hydraulic and/or electric sensors formeasuring the energy for turning the mixing drum, speed sensors formeasuring the speed of rotation, temperature sensors for monitoring theatmospheric temperature as well as the mix temperature, and dispensingequipment, as well as the computer processing units (CPU) for monitoringsignals from the sensors and actuating the dispensing equipment are bynow relatively well known in the industry. For example, such slumpcontrol systems, which can be used optionally in association withwireless communication systems, are disclosed in U.S. Pat. No.5,713,663; U.S. Pat. No. 6,484,079; U.S. Ser. No. 09/845,660(Publication no. 2002/0015354A1); U.S. Ser. No. 10/599,130 (Publicationno. 2007/0185636A1); U.S. Pat. No. 8,020,431; U.S. Ser. No. 11/834,002(Publication no. 2009/0037026); and WO 2009/126138.

A further exemplary system for monitoring and control using wirelesscommunications in combination with sensors for monitoring variousphysical properties of the concrete mix is taught in U.S. Pat. No.6,611,755 of Coffee. These teachings, as well as the patent referencesas previously discussed in the background section above, are expresslyincorporated herein by reference.

Also known in the industry (though perhaps to lesser extent) aresophisticated methods for monitoring and obtaining information about thequantity and/or characteristics of cementitious material in mixing drums(including slump and air content) by analyzing energy waveforms (e.g.,hydraulic pressure), and, more preferably, by converting time-domainwaveforms into frequency-domain spectra, whereby further information maybe obtained and assessed. Such teachings are found in World PatentApplication No. WO 2010/111,204 (entitled “Mixer Waveform Analysis forMonitoring and Controlling Concrete”) of Koehler et al., incorporatedherein by reference.

Thus, exemplary concrete mixing drums believed to be suitable for use inthe present invention are those that are rotatably mounted on ready-mixdelivery trucks, as mentioned above, or on stationary mixers as may befound in commercial mixing plants. The inner drum surfaces, particularlyof truck mixing drums, tend to have at least one mixing blade that mixesaggregates within the concrete.

It is believed that a number of exemplary embodiments of the inventionmay be practiced using commercially available automated concrete mixmonitoring equipment with little or no modification to the hardware, aswould be apparent in view of the invention disclosed herein. Suchconcrete mix monitoring equipment is available from VERIFI LLC of WestChester, Ohio, under the trade name VERIFI®.

The concept of “dose response” as used herein shall mean and refer tothe effect of a particular additive as a function of the administereddose of cement dispersant (e.g., water and/or chemical admixture) and ofan ACA (chemical admixture) on a rheology property (e.g., slump) andentrained air property in a hydratable cementitious mix such asconcrete. This concept has particular relevance to FIGS. 1 through 5,which illustrate how the present invention functions to permit rheology(e.g., slump) and entrained air content targets to be prescribed by theend user (e.g., contractor, customer, truck operator, or other customer)and to be achieved by the system (e.g., hardware/software mounted onready-mix truck, or connected to concrete plant stationary mixer, etc.).

As illustrated in FIG. 1, the methods of the present invention permit anoperator to specify, into the CPU of a mix process control system, arheology target (such as slump, which will be used in this section forillustrative purposes, expressed in terms of slump in inches, the slumptarget being most often expressed as a range) as designated as at“S_(T)”; and an air content target (e.g., in terms of percentages basedon volume of concrete, usually expressed as a range) as designated as at“A_(T)”. The point designated as at “1” represents the current slump andair content of the concrete mix being mixed in the concrete mixer, whilethe Slump-Air targets (S_(T) and A_(T)) are illustrated as a rectangle,designated as at “2.” The Slump-Air targets are defined respectively interms of slump in length (e.g. inches or mm) and entrained air contentas a percentage of concrete volume. The CPU is programmed to retrievefrom CPU-accessible memory (which may, for example, be stored on theconcrete ready-mix truck or accessed through electronically and/orwirelessly to a central dispatch or control center) at least four setsof data containing correlations. These at least four correlations referto data sets regarding the effects of ACA and cement dispersant inconcrete, including: (i) effect of cement dispersant on rheology (e.g.,slump where S_(T) has been specified); (ii) effect of ACA on aircontent; (iii) effect of ACA on rheology (e.g., slump where S_(T) hasbeen specified); and (iv) effect of said cement dispersant on aircontent.

Thus, FIG. 1 represents by the arrow designated as at “3” the change inboth the (entrained) air content and the slump for dosage increases inthe air control admixture component; while the arrow designated as at“4” represents the change in both air content and the slump for dosageincreases in the cement dispersant component. The arrow designated as at“5” represents the combined effect on air and slump with dosageincreases in the two components.

The aforementioned four sets of data correlations are illustratedgenerally in FIG. 2 through FIG. 5, each of which, for the sake ofsimplicity, shows two “curves.” In FIG. 2, current slump (in terms ofinches concrete) is plotted against cement dispersant (“HRWR” refers toHigh Range Water Reducer) required to change slump by one inch. In FIG.3, entrained air content (in terms of percentage based on volume ofconcrete) is plotted against AEA required to change air content by onepercent. Similarly, FIG. 4 illustrates slump (inches) plotted againstAEA required to change slump by one inch. Finally, FIG. 5 illustratesentrained air content plotted against cement dispersant (“HRWR”)required to change air content by one percent.

In each of FIGS. 2 through 5, two exemplary curves are shown. In FIGS. 2and 4, each curve may represent different current air content. In FIGS.3 and 5, each curve may represent different current slump.

In preferred methods and systems, each of these data correlations asillustrated in FIGS. 2 through 5 should be based on a plurality of datasets. An example is provided in the case of cement dispersant effect onslump as shown in FIGS. 7 and 8. FIG. 7 illustrates a plurality of datacurves for various cement dispersants in different concrete mixes. FIG.8 illustrates that an average or median value can be obtained orgeneralized from the data set and used for adjusting and dosing theconcrete mixes. This approach is applicable to each of the data setcorrelations which have been graphically illustrated in FIGS. 1-4, andthus employed in the implementation for the method of monitoring andadjusting air and slump which was graphically illustrated in FIG. 1.

FIG. 6 is a graphic illustration of alternative method of the presentinvention whereby current slump (inches) of concrete is measured as afunction of the ratio of the amount of change in entrained air content(%) divided by the amount of change in slump (inches) for a given dosageof a chemical admixture. This shows that for a current slump value, bothair and slump will change when a given admixture is used. The amount ofthis change can be represented graphically. This graph can be updated asadditional data is collected.

The present inventors would like to acknowledge at this point that FIGS.7 and 8 are derived from related U.S. patent application Ser. No.12/821,451 filed on or about Jun. 23, 2010 (entitled “Method forAdjusting Concrete Rheology Based Upon Nominal Dose-response Profile”).In '451, Koehler et al. described an unexpected dose response behaviorwhich appeared when different concrete mixes, into which a(polycarboxylate) cement dispersant was admixed, demonstrated similarlyshaped dose response curves, wherein slump was shown as a function ofthe dose amount (ounces of admixture per cubic yard of concrete)required to change slump by one unit (such as from 2 to 3 inches slump,and from 3 to 4 inches slump, and so on). The calculation of a nominaldose response (“NDR”) profile was illustrated therein in FIG. 2 (and inthe present application herein as FIG. 7) wherein at least two profilecurves (labeled “maximum dose” and “minimum dose” for convenientreference) are considered to provide one NDR profile.

As discussed in U.S. Ser. No. 12/821,451, the significance of thenon-intersecting behavior of the nominal dose response curves (See e.g.,FIG. 7 herein) led Koehler et al. to the realization that one couldadjust concrete rheology through use of an NDR profile or curve based oneven one curve obtained from only one data set, although using at leasttwo curves is preferred (See e.g., FIG. 2 herein), and using a pluralityof curves (See e.g., FIGS. 7 and 8 herein) is most preferred from thestandpoint of accuracy. The NDR profile can be adjusted by scaling onlyone parameter—namely, a ratio reflecting the actual admixtureperformance and that predicted by the NDR curve. Thus, an adaptivecontrol methodology can be used to update the NDR curve informationbased on actual admixture performance. Each dose of admixture isselected by using the NDR curve adjusted by the scaling factor fromprevious additions of admixture into the same load of concrete. Thus,the doses selected are adjusted to the actual conditions associated withthe concrete load without the need to measure and adjust explicitly forthese parameters. In such case, the second and each subsequent doses ofadmixture within a load are likely to be significantly more accuratethan the first dose. This eliminates a lengthy trial-and-error processwhere previous performance of admixture in the load of concrete is notconsidered. (Please note that the term “admixture” as used herein mayrefer to water and/or chemical additive in the case of cementdispersant).

The following explanation is taken from U.S. Ser. No. 12/821,451 ofKoehler et al., which only described how one concrete property at a time(e.g., slump, air content) could be assessed. Koehler et al. did notteach or suggest how both rheology and air content could besimultaneously monitored or controlled through an integrated approach,as in the present application. The rheology of a given concrete mix canbe adjusted by inputting into a computer processor unit (CPU) only theamount of the concrete (load size) and the target rheology value (e.g.,slump, slump flow, or yield stress), and comparing the actual rheologyto the NDR profile, adding a percentage of the nominal dose the chemicaladmixture that would be (theoretically) required to change the actualrheology to the target rheology, measuring the resultant change inrheology value and comparing this to the NDR value that wouldtheoretically have been obtained using the percentage nominal dose, andthen adjusting the rheology by adding a subsequent dose which takes intoaccount the deviation measured as a result of the first percentageaddition. One may therefore take into account a “learning” step to beincorporated into the methodology, without having to consider numerousparameters such as temperature, mix design, humidity, and other factors.

In U.S. Ser. No. 12/821,451, an exemplary method for controllingrheology in a concrete mixer wherein the energy required for operatingthe mixer is measured and correlated with a nominal rheology value andwherein a rheology-modifying agent (cement dispersant) is added into thecementitious composition to modify its rheology is said to comprise: (a)entering into a computer processor unit (“CPU”) a target rheology value(“TRV”) and load size for a hydratable cementitious compositioncontaining or intended to contain a particular rheology-modifying agentor combination of rheology-modifying agents; (b) obtaining a currentrheology value (“CRV”) of hydratable cementitious composition containedwithin a mixer; (c) comparing through use of CPU the current rheologyvalue obtained in step (b) against a nominal dose response (“NDR”)profile stored in CPU-accessible memory and wherein said NDR is based onat least one data set wherein various dose amounts of a particularrheology-modifying agent or combination of rheology-modifying agents andtheir correlative effect on rheology value (such as slump, slump flow,or yield stress) is retrievably stored, and determining the nominal doseof said particular rheology-modifying agent or combination ofrheology-modifying agents required to change the obtained CRV to the TRVspecified in step “(a)”; (d) dosing the hydratable cementitiouscomposition in a mixer with a percentage of said particularrheology-modifying agent or combination of rheology-modifying agentsthat is selected or pre-selected from 5% to 99% based on the nominaldose determined in step (c) required for changing said obtained CRV tosaid TRV as specified in step (a); (e) obtaining a subsequent CRV of thehydratable cementitious composition after the percentage of the nominaldose of the particular rheology-modifying agent or combination ofrheology-modifying agents selected or preselected in step (d) is addedinto and uniformly mixed with said hydratable cementitious composition;comparing the dose selected or preselected in step (d) to the doseaccording to the NDR profile for the same change in the rheology valuefrom step (b) to step (e), and determining the scaling factor (“SF”) bywhich to adjust the dose from the NDR profile, where SF is defined asthe actual dose from step (d) divided by the nominal dose to achieve thesame change in rheology value indicated by the NDR profile; and (f)mixing into the hydratable cementitious composition the particularrheology-modifying agent or combination of rheology-modifying agents inan amount calculated in terms of SF multiplied by the dose from the NDRprofile indicated to convert the current CRV measured in step (e) to theTRV specified in step (a). If the target rheology value such as slump isnot attained upon completion of the steps, (which can be due to anynumber of factors, such as temperature or humidity change), then processsteps (e) and (f) can be repeated as required. In addition, concreterheology changes over time.

Each time the rheology value decreases by a certain amount, arheology-modifying agent (e.g., chemical admixture) must be added torestore the rheology value. Steps (e) through (f) can be repeated toadjust the rheology value.

Thus, NDR profiles are calculated based on an average of at least twodose response curve values (see e.g., FIG. 8 herein), and, morepreferably, an average of a plurality dose response curve valuesobtained from trialing the particular rheology-modifying agent orcombination of rheology-modifying agents (See e.g., FIG. 7 herein).

It was further taught in U.S. Ser. No. 12/821,451, that the system CPUcan be programmed to assume a learning mode, whereby batch histories canbe incorporated into the NDR profile which is then stored intoCPU-accessible memory, and/or the scaling factor can be redefined sothat dosing can be rendered more accurate. In other words, the rheologyvalue changes effected by doses of the rheology-modifying agentadministered during a concrete mix delivery operation are incorporatedinto the nominal dose response (NDR) curve or scaling factor whereby theNDR curve or scaling factor (SF) is modified; and rheology value changesin a subsequent concrete mix delivery operation or operations areeffected based on the modified NDR curve or modified SF.

The CPU is programmed to dose the hydratable cementitious composition inthe mixer using a selected or pre-selected percentage of the idealamount of the rheology modifying agent (cement dispersant component)that would be determined by the NDR profile to change the currentrheology value to the target rheology value that was previously entered.That percentage may be 50% to 95% of the ideal (or nominal) amount, andmore preferably would be about 50%-90%; and most preferably would be50%-80%. Generally, the lower percentage in these ranges is preferablefor this first dose until confidence is obtained.

The CPU would also be programmed to obtain a subsequent current rheologyvalue (e.g, slump) of the concrete after the percentage of the nominaldose of the particular rheology modifying agent (e.g., cementdispersant) was added into the concrete. The CPU would compare thenominal (or theoretical) effect on the rheology value of the percentagedose selected or preselected to the subsequent rheology value anddetermine the scaling factor by which to adjust the dose from the NDRprofile. The scaling factor is thus defined as the actual dose dividedby the nominal dose to achieve the same rheology change as indicated bythe NDR profile.

The CPU would be further programmed to mix into the concrete the dose ofthe admixture. The amount of this subsequent dose would be calculated bymultiplying the scaling factor (SF) by the amount theoretically needed,according to the NDR profile, to change the subsequent current rheologyvalue measured to the target rheology value previously specified by theoperator.

The foregoing CPU program steps may be repeated whenever the currentconcrete property is sensed to be less than or greater than the targetconcrete property, when compared to a given (inputted or pre-programmed)threshold. This may be done automatically, for example, by programmingthe CPU to repeat the steps when the difference between the current andtarget values exceed a predetermined amount and thus are determined tobe in non-conformance with each other. If the difference between thecurrent and target values is less than the predetermined amount, the CPUcan also be programmed to trigger an alarm to indicate to the operatorthat the concrete mix is ready to be discharged and poured.

Thus, an NDR profile or curve can be derived from an average of at leasttwo curves representing the behavior of a given admixture on theconcrete, as illustrated in FIGS. 2-6, and more preferably the NDR isestablished using an average of a plurality of dose response curves forthe particular chemical admixture(s), as illustrated in FIG. 7. The doseresponse curves of FIG. 7 in particular suggest, by the varying curveamplitudes, that various parameters such as concrete mix design,temperature, degree of hydration, water/cement ratio, and aggregateamounts might be varying slightly (or even significantly) from batch tobatch. Still, the fact that the various dose response curves did notintersect led the present inventors to realize that these other variousparameters did not necessarily need to be kept constant in order toestablish a nominal dosage response (NDR) profile because the average ofthese dose response curves would have similar behavior in terms ofcalculating amounts of admixture needed for changing the property of theconcrete mix from (e.g., slump) one value to the next (e.g., from slumpof 2 inches to five inches).

Another way of viewing the NDR profiles is to realize that they involvedata sets having at least one non-homogeneous parameter, such asconcrete mix design, temperature of concrete, degree of cementhydration, water/cement ratio, and aggregate amount or cement/aggregateratio. These may be varied from batch to batch in the data sets which goto make up the NDR profile (See e.g., FIG. 1).

U.S. Ser. No. 12/821,451 disclosed many of chemical cement dispersantsas previously mentioned could be used, and emphasized that so long asthe same rheology-modify agent or combination of rheology-modifyingagent is being used as was previously trialed for creating the nominaldosage response (NDR) profile, then other variables such as concrete mixdesign, amount of water or cement or water/cement ratio, aggregateselection or composition, degree of hydration, do not necessarily needto be inputted into the CPU and remain optional.

The present invention is believed to be a patentable improvement uponSer. No. 12/821,451 in that it allows for targets in rheology andentrained air properties to be simultaneously specified and integratedinto the monitoring/process control system, and also allows for separateaddition of rheology modifier (e.g., cement dispersant with or withoutair entrainer and/or air detrainer) and separate addition of air controlagents (e.g., air entrainer and/or air detrainer), despite the fact thatthe relationship between air entrainer effects and dispersant (slump)effects have been non-linear and historically unpredictable.

In order to achieve this, the present invention provides a “multivariatemanagement” capability that has not been achieved, disclosed, or evensuggested before. As summarized above, an exemplary method of thepresent invention for monitoring and adjusting entrained air andrheology levels in a cementitious mix, comprises:

(a) providing a concrete mix in a rotatable concrete mixer, saidconcrete mix comprising hydratable cement, aggregates, and water forhydrating said cement, and said concrete mix having a total volume whenmixed uniformly of 1.0 to 15.0 cubic yards;

(b) inputting into a computer processing unit (CPU) and storing intocomputer accessible memory desired concrete performance ranges relativeto: a slump (rheology) target or target range (hereinafter “S_(T)”)wherein a desired concrete slump or slump range is specified within arange of 0-11 inches; and an air content target or target range “A_(T)”wherein a desired concrete air content or air content range is within arange of 1% to 10%;

(c) operating said concrete mix in said rotatable concrete mixerandobtaining at least one slump value in current time (hereinafter“S_(CT)”) and at least one air content value in current time(hereinafter “A_(CT)”);

(d) comparing using CPU said S_(CT) against said S_(T) and said A_(CT)against said A_(T) until detection by CPU of a non-conformance event,wherein said S_(CT) does not conform with said S_(T) or said A_(CT) doesnot conform with said A_(T); and

(e) introducing into the concrete mix contained in said concrete mixer,at least one of two different types of additives comprising:

-   -   at least one chemical admixture for modifying air content in the        concrete mix (hereinafter “ACA”), wherein said at least one ACA        comprises at least one Air Entraining Admixture (hereinafter        “AEA”), at least one Air Detraining Admixture (“ADA”), or        mixture of at least one AEA and at least one ADA; and    -   at least one cement dispersant for modifying rheology of the        concrete mix, said at least one cement dispersant comprising at        least one polymeric dispersant, water, or a mixture of said at        least one polymeric dispersant and water;        said introducing of said at least one ACA and cement dispersant        being achieved by CPU-controlled valve system in accordance with        CPU-accessed memory device having at least four sets of data        correlations:    -   (i) effect of said cement dispersant on rheology (e.g., slump);    -   (ii) effect of said ACA on entrained air content;    -   (iii) effect of said ACA on rheology (e.g., slump); and    -   (iv) effect of said cement dispersant on entrained air content.        It should be understood that in the description of the method        steps (a) through (e) above, slump is given as an example of        rheology, and that monitoring and adjustment of other rheology        factors such as slump flow, DIN flow, yield stress, etc., can be        substituted for the slump targets and current slump values        designated respectively as at S_(T) and S_(CT).

As described in Step (b), the operator inputs into a computer processorunit (“CPU”) at least two pieces of information: a target rheology value(e.g., slump, slump flow, DIN flow, yield stress, etc.) and target aircontent. The operator may also be required to input the load size forthe concrete that will be placed into the mixer (and hence furtherexemplary methods involve inputting of the load size). The input ofthese prescribed or target data points may be performed by the batchmaster at the ready-mix plant, by the truck driver, or foreman at theconstruction site. Indeed, this input may be performed by anyone incharge of the concrete delivery, and it does not require the inputtingof other parameters such as temperature, humidity, and other factorswhich are optional.

Also as mentioned above, the target rheology value may be any of therheology factors whose measurement in unit values are customarilyemployed, such as: slump (customarily measured in terms of length units,e.g., inches); slump flow (length, e.g., inches); yield stress(customarily measured in terms of stress, e.g., pounds per square inchor pascals); viscosity (pascals.seconds); flow (length); and thixotropy(pascals/second). Load size can be inputted into the CPU in terms oftotal weight or volume of the batch concrete (e.g., cubic yards)including all of the components. If the target rheology value (or range)is defined in terms of slump, then the measument for slump can be donein accordance any number of standard measurements (see e.g., ASTM C143-05, AASHTO T 119, or EN 12350-2). If the target rheology value isdefined in terms of slump flow, this measurement can be done inaccordance with ASTM C1611-05. If the target rheology value is definedin terms of the flow table test, this can be done in accordance with DINEN 12350-5 (sometimes referred to as “DIN flow”).

It is important that the “at least four sets of data correlations”mentioned in Step (e) include the same or similar chemical admixturecomponents as those being used for dosing into the concrete, as well asthe same or similar concentrations of such components. For example, ifthe “cement dispersant” component for modifying rheology of the concretemix, as mentioned in Step (e), comprises one or more particularpolymeric cement dispersants (which optionally may be formulated withother admixtures such as AEAs, ADAs, accelerators, and/or retarders),then it is important that the set of data correlations mentioned in Step(e) include the identical or similar polymeric cement dispersant(s) asformulated with any other admixtures that may be present in the productformulation as those being used for dosing into the concrete. The sameapplies to the chemical admixture or admixtures for modifying entrainedair level (“ACA”) as mentioned in Step (e). The identical or similarAEAs and/or ADAs should be used for the set of data correlations asthose being used for dosing into the concrete.

It is preferable that each of the “at least four sets of datacorrelations” mentioned in Step (e) be based on a plurality of nominaldose response (NDR) curves or profiles derived from the same componentbeing dosed into the concrete. Hence, one will need to generate new NDRprofiles for a cement dispersant package component, to the extent thatadding or omitting a particular active ingredient from the chemicaladmixture(s) formulation is seen to affect rheology and to affect aircontent. If for example a desired swap in the cement dispersant packagecomponent affects both rheology and entrained air levels, one needs togenerate new NDR profiles for each of the rheology behavior as well asentrained air behavior.

Among the benefits of using NDR profiles is that they areself-correcting, and they may possibly allow for high accuracy, evenwhere the cement-dispersing polymer is different and where other activeingredients might be different in nature and amount. However, when usingthe method of the present invention, it is preferable to start with thesame cement dispersants and same ACAs to compensate for any differencesin their concentrations.

In Steps (c) and (d) of the exemplary method of the present inventionbeing described herein, it is necessary for the CPU to determine thecurrent rheology state and current air content value of the concretecontained within the mixer. This is stored in CPU-accessible memorybecause it will provide a reference point for later steps.

In Step (d) of the exemplary method, the CPU compares the currentrheology state and current entrained air value obtained in Step (c) withtarget values that were inputted in Step (b). If there is a discrepancy,such as the current entrained air value falling outside of the rangespecified in Step (b), then the CPU will access one or more of the setsof data correlations (i) through (iv) mentioned in “Step (e).”

Preferred methods and systems of the present invention employ at leastfour different sets of data correlations, each of which are preferablygenerated using a plurality of data sets (e.g., curves or profiles). Inother words, as described in Step (e), a plurality of NDR profilesshould be generated and stored relative to: (i) the effect of the cementdispersant on rheology (e.g., slump); (ii) the effect of the ACA onentrained air content; (iii) the effect of the ACA on rheology (e.g.,slump); and (iv) the effect of the cement dispersant on entrained aircontent.

As previously mentioned, the “cement dispersant” component may comprisewater, one or more chemical admixtures such as a polycarboxylate polymertype admixture, or even both, and this cement dispersant component mayfurther comprise an AEA, ADA or mixture thereof; while the “ACA”component can comprise same or similar AEA, ADA, or mixture thereof.

In many cases, it is expected that the adjustment of the currentrheology value or current air content of the concrete mix, such thatthese will fall within targets, can be accomplished using either cementdispersant component or ACA component, or combination of both.

In this light, it can be evident that FIG. 1 illustrates the situationwhere the current air content (as illustrated by the point designated asat “1”) is expected to be below target air content (“A_(T)”) such thatan AEA will need to be added into the concrete to elevate air content toreach the target “2” (rectangle). In most cases, the present inventorswould expect the point (“1”) representing current air and slump to belocated below and left of the rectangle in most cases; and it could bepossible that the point 1 could be located to the left of, but alsolocated above, the rectangle 2 in which case an Air Detraining Agent(ADA) would need to be added into the concrete to decrease entrained aircontent to reach the target “2” (rectangle).

It will also be evident that FIG. 1 illustrates the situation where,based on the data being graphically illustrated by the entrained aircurve “3” and slump behavior curve “4,” both an AEA and cementdispersant will need to be added to move air and slump properties of theconcrete mix within the target “2” (rectangle). If the current air orslump properties (shown as point “1” in FIG. 1) were closer to thetarget “2,” it could be possible to introduce either the ACA or cementdispersant component alone into the concrete mix in order to attain thetarget “2.”

In cases where both of the ACA and cement dispersant need to be addedinto the concrete mix so that as to attain the target “2,” the CPU canbe programmed to specify whether the components are to be favored interms of volume amount being introduced into the concrete. Furtherexemplary methods and systems of the present invention, therefore,include the additional step of inputting a preferred addition order orpercentage of the ACA or cement dispersant component. If the cementdispersant component were comprised of only or mostly water, it may bedesirable to introduce the ACA component to attain the target “2” (aslarge water content in the concrete mix could potentially decreasestrength properties of the concrete). On the other hand, if economy isthe primary goal, the CPU can be programmed to make a benefit/costdetermination, such that the least expensive component is used forachieving the necessary adjustment needed for attaining the target “2”.

Generally, however, it is expected that if the current slump wasdetermined to be outside of the target slump range, the cementdispersant would be used to make an adjustment such that the currentslump of the mix is brought back to within the target slump range. Ifboth the current slump and current entrained air content are determined(Step (d)) to be in nonconformity with the target ranges inputted intoStep (b), then the CPU will access the sets of data correlations storedin computer-accessible memory, and send a signal to a valve forinjecting a particular amount of cement dispersant into the concrete mix(where the NDR profiles provide that the adjustment of the mix to thetarget slump and entrained air content can be made using the amount ofcement dispersant alone); or the CPU will send signals to two valves,one for introducing the cement dispersant into the concrete mix, theother for introducing ACA into the concrete mix, where the use of cementdispersant alone would not be sufficient for adjusting the currententrained air content such that it conforms with the target range forair content (as inputted at Step ((b)).

It could also be the case that the CPU could select the ACA alone to beinjected into the concrete mix, where both the current air content andslump were determined to be in non-conformance with the target aircontent and rheology, provide that a particular amount of ACA weresufficient to adjust both the current rheology and entrained air contentsuch that they could be made to conform to the target range (as inputtedat Step (b)).

In further exemplary methods and systems of the invention, the NDRcurves are preferably based on at least four sets of data correlationsinvolving at least one non-homogeneous parameter selected from concretemix design, concrete mix ingredient source, temperature, degree orextent of hydration, water/cement ratio, and aggregate amount. As theuse of more NDR curves are used in establishing a profile, at least twoor three, or even more, of these non-homogeneous parameters may occurwithout hindering reliability of using the NDR profiles for adjustingair and slump of concrete mixes.

In further exemplary methods and systems, the data regarding changes inentrained air and rheology on the concrete mix as effected by doses ofACA and cement dispersant administered during a concrete mix deliveryoperation are incorporated into the nominal dose response (NDR) curvesand scaling factors whereby NDR curves and scaling factors (SF) aremodified; and subsequent air and rheology changes in the same or asubsequent concrete mix delivery operation are effected based on themodified NDR curves and/or modified SF data.

In still further exemplary methods and systems, the CPU communicateselectronically and/or wirelessly with CPU-accessible database memoryhaving data relative to said changes in entrained air and rheology onconcrete mixes as effected by doses of ACA and cement dispersantadministered during concrete mix delivery operation and incorporatedinto said nominal dose response (NDR) curves and scaling factors wherebysaid NDR curves and scaling factors (SF) are modified, as well as datarelative to air and rheology changes in the same or a subsequentconcrete mix delivery operations as effected based on said modified NDRcurves or modified SF.

For example, it is contemplated by the present inventors, that the atleast four sets of data correlations can be transferred by cable orwireless transmission (e.g., flash drive, internet, radio frequency,etc.) to a central computer data base (such as located at centraldispatch location or other office) from which it can be accessed byindividual CPUs within the mixing truck fleet.

Still further exemplary methods and systems of the present invention maycomprise the use of NDR profiles derived from at least four data setcorrelations (See Step (e)(i) through (e)(iv) each of which involvesconcrete mix operations involving at least two non-homogeneousparameters, and even more than two non-homogeneous parameters, selectedfrom different concrete mix design, concrete mix ingredient source,temperature, hydration, water/cement ratios, different aggregate amountsor ratios, and concrete mix designs. So long as the particular admixturecomponents (e.g., water and/or concrete admixture or combination ofchemical admixtures) used for setting up the NDR profiles and forobtaining a current entrained air values and rheology (slump) valuesis/are identical or substantially similar, the slope behavior of the NDRcurves is similar from one air value or rheology value unit to the next.In fact, even if two or more admixtures vary in composition but aresimilar in performance, it may be possible to use the same NDR profilefor all such admixtures.

In further exemplary embodiments of the invention, the process ofmonitoring entrained air and rheology changes can involve the use ofmore than one type of ACA and more than one type of cement dispersant,with each type of admixture component having its own scaling factor, NDRprofile, or both. For example, one can establish NDR profiles forcombinations of ACA components and cement dispersant components witheach of these further comprising one or more additional additives,including: viscosity modifying agents (e.g, thickeners, thixotropymodifying agents); set accelerators, set retarders, or mixture thereof;corrosion inhibitors, water repellents, strength enhancing agents; andother additives and mixtures thereof.

In still further exemplary methods and systems of the invention, morethan one air and/or rheology target can be specified and met within thesame concrete mix delivery operation. For example, one may use multipleair and/or rheology targets, such as air and/or slump target(s) duringtransit (from batching or plant operation to job site) and duringplacement (after the truck arrives at the job site where the mix is tobe poured). As another example, one may define two different targetsthat the concrete mix will attain within the same deliveryoperation/process and at the same time, such as slump flow and plasticviscosity. It is possible, in other words, to have onerheology-modifying agent or combination of agents (e.g., admixturepackages) for modifying the slump flow (characterized by the spreadingof concrete from a removed slump cone) and to have anotherrheology-modifying agent or combination of agents for modifying theplastic viscosity (characterized by shear stress divided by the shearrate).

In a further exemplary embodiment, the scaling factor is calculated as aweighted average of all dose responses in a given load or mix design. Inother words, in a series of delivery operations in which various scalingfactors are derived, the scaling factor used in the current deliveryoperation can be based on an average of all scaling factors computed,but primarily based on data obtained from the most recent deliveryoperations.

The correlations between the effect of the ACA admixture component andrheology modifying admixture component on the respective properties ofthe concrete mix (e.g., air and slump) can be calculated using variousmethodologies.

The four data correlations which can be stored in computer-accessiblememory for use by the CPU (e.g., effect of cement dispersant on slump,effect of cement dispersant on air, effect of ACA on slump, and effectof ACA on air) can be calculated, for example, using the followingrepresentative function:

0=a(Sp)^(m) +b(ACA)^(n) +c(S _(CT))^(o) d(A _(CT))^(p) +e(S _(T))^(q)+f(A _(T))^(r)

wherein a, b, c, d, e, f, m, n, o, p, q, and r are empirical regressionvalues determined from past data and “Sp” represents the amount of slumpmodifying admixture (e.g. volume), “ACA” represents the amount of AirControlling Admixture, “S_(CT)” represents rheology at the current time(e.g., slump as may be determined for example in accordance with ASTM143), “A_(CT)” represents air content at the current time in terms ofpercentage total volume of concrete; “S_(T)” represents the target slump(ASTM 143), “A_(T)” represents the target entrained air content in termsof percentage total volume of concrete. During a concrete delivery, allparameters except Sp and ACA are known. The empirical regression valuesare determined from past concrete data. The values of S and A aredetermined by the measurement equipment on the truck. The values ofS_(T) and A_(T) are programmed into the CPU. Therefore, it is necessaryto solve for the values of Sp and ACA. This can be done using knownnon-linear optimization techniques. Because there are two unknownvariables, additional constraints must be set. These could include, forexample: minimize Sp, minimize ACA, or minimize cost. In addition, allvalues for Sp and ACA must be non-negative.

In still further exemplary embodiments, it is contemplated that morethan four different sets of data correlations may be stored inCPU-accessible memory for the purpose of adjusting properties of theconcrete mix using more than two chemical admixtures. For example,methods and systems of the present invention can permit adjustment ofthe air and/or rheology of the concrete mix through three or moreseparate admixture components, such as: (1) cement dispersant (waterand/or chemical admixture); (2) air entraining agent, and (3) airdetraining agent. In this case, the database will have six sets of datacorrelations (or NDR curve profiles) based on the effect of each ofthese three components on, respectively, the entrained air and rheology(slump) of the concrete, as well as the scaling factor data foradjusting the concrete values through controlled additions of the threecomponents.

In still further embodiments, the CPU-accessible database memorycontains stored information or data regarding one or more of concretemix design, concrete mix ingredient source, concrete temperature,water/cement ratio, and time since batching for each data point relativeto said changes in entrained air and rheology of concrete mixes asaffected by doses of ACA and cement dispersant administered duringconcrete mix delivery operation.

In still further embodiments, the CPU-accessible database memorycontains stored information or data regarding one or more of concretemix design, concrete mix ingredient source, concrete temperature,water/cement ratio, and time since batching and one or more of thesedata is used to select the nominal dose response curve or scalingfactor.

The methods of the invention are expected to be employed for measuringand adjusting any rheology characteristic of the concrete, includingslump, slump flow, and yield stress. Measurement and adjustment of slumpwill probably of greatest concern, but the inventors believe that otherrheology characteristics such as slump flow or DIN flow could bemonitored and adjusted using the present invention methodologies.

In further exemplary methods of the invention, the method of theinvention wherein both ACA and cement dispersant components are fed intothe concrete mixer when the concrete mix is monitored and found to be innon-compliance with slump and air content targets can be suspended for aportion of the delivery trip, wherein the CPU can be programmed simplyto add the concrete dispersant component in order to reach rheologytarget (or targets), and possibly also to reach air content target. Itmay be possible, after concrete ingredients (e.g., cement, aggregates,water) are loaded into the mixer to make the concrete mix, that only thecement dispersant component (water, water reducing admixture such as asuperplasticizer) needs to be added until the concrete mix reaches R_(T)and A_(T) and the concrete can be maintained using only water reducingadmixture to maintain both R_(CT) and A_(CT) within R_(T) and A_(T).Thereafter, when the delivery mix truck approaches and/or enters theconstruction site, the CPU can be programmed to activate use of bothwater-reducing admixture and ACA in order to maintain both R_(CT) andA_(CT) within R_(T) and A_(T).

In still further exemplary methods, concrete should be mixed aprescribed amount to ensure the cement dispersant or AEA is fullydistributed throughout the mix. For example, if concrete is mixed in arotatable mixing drum, the number of revolutions required for fullmixing can be set based on the identity of the cement dispersant and/orACA added. This full mixing should be provided prior to dischargingconcrete or repeating step (c).

The following examples are provided for illustrative purposes only, andare not intended to limit the scope of the present invention.

Example 1

The following section describes how to generate a dosage response curveor profile for a given admixture, in this case a cement dispersant usedfor generating a slump profile. A concrete mixture is made in alaboratory mixer without any chemical admixtures added. Slump ismeasured by removing sample portions of concrete and placing them in aslump cone in accordance with ASTM C143-05. Air content is alsomeasured. When this test is done, the tested mixture is discarded.Immediately thereafter, another concrete mixture having the sameconcrete mix design is made in the same laboratory mixer, but this timewith a chemical admixture (e.g., polycarboxylate polymer cementdispersant). Slump and air content are again measured. When this testwas done, the mixture is discarded. A number of further successivesamples based on identical mix factors (e.g., temperature, type ofcement, amount of air and water, water/cement ratio, etc.) can be madein the laboratory mixer, but each varying only in the dosage amount ofthe admixture. Except for the admixture dose, all other variables shouldbe kept constant. Each successive mixture should be discarded aftertesting. The resultant data, if plotted, will resemble one of theplotted lines shown in FIGS. 2 and 5.

The above process is then repeated, but for each reiteration one of themix factors is varied while all other mix factors were kept constant.The varied mix factors can include: temperature of the materials, theamount and type of cement, type of fine aggregate, type of coarseaggregate, amount of air in concrete, amount of water, and ratio ofwater to cement. The data for these concrete mixes having a varied mixfactor are also plotted as various lines shown in FIG. 1.

Surprisingly, when the above method was performed, it was discoveredthat the dosage response curves, as shown in FIG. 7, did not intersect.The concrete mix property (slump for example) can be adjusted byreference to the behavior of any curve or an average of all such dosageresponse curves, and the behavior of such curve or plurality of curvescan serve as a nominal or reference dosage response curve during realtime production-operation.

(As previously explained, FIG. 8 is a simplified version of FIG. 7showing “minimum,” “maximum,” and average dosage response curves. Theaverage dose response curve shown in FIG. 7 can serve as a nominaldosage response curve during real time production-operation).

Example 2

The NDR profile or curves based on polycarboxylate cement dispersantmentioned in Example 1 above was tested in the field using a concretemix truck having an automated monitoring and dosing system provided byVerifi LLC of Ohio available under the trade name VERIFI®. Thismonitoring system measured slump based on hydraulic pressure and mixdrum speed. This system can also inject cement dispersant admixture intothe mix drum from a small chemical storage tank mounted on the fender.(See also US Patent Publication 2009/0037026 of Sostaric et al.). Over aperiod of months, a variety of concrete mixes were prepared in theconcrete mix truck. A nominal dose response profile was obtained,similar to that described above in Example 1, and this was used as thereference or “nominal” reference dose (“NDR”) profile.

A number of tests were run using the exemplary method of the inventionfor different concrete mix delivery operations, wherein the NDR was usedby the computer processing unit of the automated monitoring and dosingsystem for each successive concrete mix sample prepared in the mix drum.Mixes produced in the drum over the next few weeks experienced naturalvariations in terms of temperature, raw materials, mixture proportions(e.g., water/cement ratio, water/aggregate ratio, fine/coarse aggregateratio, etc.). And water reducing admixture (polycarboxlate cementdispersant) was dosed in accordance the NDR profile.

The use of NDR profile as a reference to adjust the current slumpresulted in changes to the concrete mix similar to those suggested bythe NDR profile. When the NDR curve is first applied, the slump changeis then used to develop the scaling factor (SF) which is then used onthe next addition of admixture.

In further exemplary methods of the invention, concrete is mixed in themixer, after Step (e), for a number of revolutions of the concrete mixerin accordance with the identity of the cement dispersant introduced intothe concrete and/or the ACA. This is performed either before dischargingthe concrete from the mixer, or before repeating step (c). In stillfurther exemplary methods, Steps (c) through (e) are repeated, at leastonce and more preferably more than once, until the concrete isdischarged from the mixer.

FIG. 9 illustrates that the actual measured slump change values (shownby the dots) closely match the theoretical slump change values.

Example 3

It is contemplated by the present inventors that NDR profiles can begenerated from the curves based on at least four different datacorrelations, such as the effect of said cement dispersant on rheology(e.g., slump); effect of ACA on entrained air content; effect of saidACA on rheology (e.g., slump); and effect of cement dispersant onentrained air content. Preferably, the NDR profiles are based on aplurality of various delivery operations, involving heterogeneousparameters (e.g., selected from various concrete mix designs, concretemix ingredient sources, temperatures, degrees of hydration, water/cementratios, and aggregate amounts. Each of the four sets of datacorrelations (as illustrated in FIGS. 2-5 would be expected to appearwith the same or similar non-intersecting characteristic of the NDRcurves in FIG. 7). In preferred embodiments, the data could betransmitted from each individual CPU unit (e.g., in each process controlsystem for the concrete delivery mix truck, or stationary concrete plantmixer) to a central database for access in the future by the individualCPU units, so as to permit use of updated NDR profiles.

The principles, preferred embodiments, and modes of operation of thepresent invention have been described in the foregoing specification.The invention which is intended to be protected herein, however, is notto be construed as limited to the particular forms disclosed, sincethese are to be regarded as illustrative rather than restrictive.Skilled artisans can make variations and changes without departing fromthe spirit of the invention.

1. A method for monitoring and adjusting slump and air content in acementitious mix, comprising: (a) providing a concrete mix in a concretemixer drum, said concrete mix comprising hydratable cement, aggregates,and water for hydrating said cement, and said concrete mix having atotal volume when mixed uniformly within the concrete mixer drum of 1.0to 15.0 cubic yards; (b) inputting into a computer processing unit andstoring, into computer processing unit-accessible memory, desiredconcrete performance ranges relative to: a target slump or target slumprange; and a target air content or target air content range wherein aconcrete air content or air content range is within a range of 1% to10%; (c) mixing the concrete mix in the concrete mixer drum andobtaining at least one slump value in current time and at least one aircontent value in current time. (d) comparing, using the computerprocessing unit, the at least one slump value in current time againstthe slump target or slump target range and the at least one air contentvalue in current time against the target air content or target aircontent range until detection by the computer processing unit of anon-conformance event, wherein the at least one slump value in currenttime does not conform with the target slump or target slump range and/orthe at least one air content value in current time does not conform withthe target air content or target air content range; and (e) introducinginto the concrete mix contained in said concrete mixer drum, one of atleast two compositionally different additives comprising: at least onechemical admixture for modifying air content in the concrete mix,wherein the at least one chemical admixture for modifying air content inthe concrete mix comprises at least one air entraining admixture, atleast one air detraining admixture, or mixture of at least one airentraining admixture and at least one air detraining admixture; and atleast one cement dispersant for modifying slump of the concrete mix,said at least one cement dispersant comprising at least one polymericdispersant, water, or a mixture of said at least one polymericdispersant and water; said introducing of the at least one chemicaladmixture for modifying air content in the concrete mix and/or at leastone cement dispersant being achieved by computer processor unitcontrolled valve system in accordance with computer processor unitaccessed memory device having at least four sets of data correlationscomprising: (i) the effect of said cement dispersant on slump of theconcrete mix; (ii) the effect of the at least one chemical admixture formodifying air content in the concrete mix on air content; (iii) theeffect of the at least one chemical admixture for modifying air contentin the concrete mix on the slump of the concrete mix; and (iv) theeffect of said cement dispersant on air content of the concrete mix. 2.The method of claim 1 wherein said at least one chemical admixture formodifying air content in the concrete mix is an air entraining agent. 3.The method of claim 1 wherein said at least one chemical admixture formodifying air content in the concrete mix is an air detraining agent. 4.The method of claim 1 wherein said at least one chemical admixture formodifying air content in the concrete mix comprises both an airentraining agent and an air detraining agent.
 5. The method of claim 1wherein said at least one cement dispersant is a polycarboxylatepolymer.
 6. The method of claim 5 wherein said at least one chemicaladmixture for modifying air content in the concrete mix is an airentraining agent.
 7. The method of claim 1 wherein, in Step (e), said atleast four sets of correlations identified in (i), (ii), (iii), and (iv)are based on an average or mean value calculated from at least twonominal dosage response curves.
 8. The method of claim 7 wherein, insaid Step (e), said at least four sets of data correlations identifiedin (i), (ii), (iii), and (iv) are based on an average or mean valuecalculated from a plurality of nominal dosage response curves.
 9. Themethod of claim 8 wherein, in said nominal dosage response curves, saidat least four sets of data correlations involve at least onenon-homogeneous parameter selected from the group consisting of concretemix design, concrete mix ingredient source, temperature, degree ofhydration, water/cement ratio, and aggregate amount.
 10. The method ofclaim 9 wherein, in said nominal dosage response curves, said at leastfour sets of data correlations involve at least two non-homogeneousparameters selected from the group consisting of concrete mix design,concrete mix ingredient source, concrete temperature, degree ofhydration, water/cement ratio, and aggregate amount.
 11. The method ofclaim 1 wherein the changes in air content and slump of the concrete mixas affected by doses of chemical admixture for modifying air content inthe concrete mix and cement dispersant administered during a concretemix delivery operation are incorporated into said nominal dose responsecurves and scaling factors whereby said nominal dose response curves andscaling factors are modified; and subsequent air and slump changes inthe same or a subsequent concrete mix delivery operation are effectedbased on said modified nominal dose response curves or said modifiedscaling factors.
 12. The method of claim 11 wherein the computerprocessor unit communicates wirelessly with computer processorunit-accessible database memory having data relative to said changes inair content and slump of concrete mixes as affected by doses of chemicaladmixture for modifying air content in the concrete mix and cementdispersant administered during concrete mix delivery operation andincorporated into said nominal dose response curves and scaling factorswhereby said nominal dose response curves and scaling factors aremodified, as well as data relative to air and slump changes in the sameor a subsequent concrete mix delivery operations as effected based onsaid modified nominal dose response curves or modified scaling factors.13. The method of claim 12 wherein the computer processor unitaccessible database memory stores information on one or more of concretemix design, concrete mix ingredient source, concrete temperature,water/cement ratio, and time since batching for each data point relativeto said changes in air content and slump of concrete mixes as affectedby doses of chemical admixture for modifying air content in the concretemix and cement dispersant administered during concrete mix deliveryoperation.
 14. The method of claim 13 where one or more of concrete mixdesign, concrete mix ingredient source, concrete temperature,water/cement ratio, and time since batching are used to select thenominal dose response curve or scaling factor.
 15. (canceled) 16.(canceled)
 17. (canceled)
 18. The method of claim 1 wherein said cementdispersant comprises water and a water reducing admixture.
 19. Themethod of claim 18 wherein water is the cement dispersant added afteringredients are loaded into the mixing drum until reaching the targetslump or target slump range and the target air content or target aircontent range, and water reducing admixture or superplasticzer is thecement dispersant used to maintain the at least one slump value incurrent time and the at least one air content value in current time inthe target slump or target slump range and target air content or targetair content range.
 20. The method of claim 1 wherein after step (e),concrete is mixed in a rotatable mixing drum a number of revolutionsthat is based on the identity of the cement dispersant and/or chemicaladmixture for modifying air content in the concrete mix added prior todischarging concrete or repeating step (c).
 21. The method of claim 1wherein steps (c) to (e) are repeated until the concrete is dischargedfrom the mixer.